广州市大气PM_(2.5)中元素特征及重金属健康风险评价

Characteristic of elements in PM_(2.5) and health risk assessment of heavy metals in Guangzhou

目的了解广州市大气PM_(2.5)中元素的浓度、时间分布特征及其来源,评价其重金属的人群健康风险。方法于2015年1—11月采集广州市3个点位的大气PM_(2.5)样品,采用电感耦合等离子体质谱仪(ICP-MS)分析了16种元素的含量,利用富集因子法和因子分析法识别16种元素的主要来源,采用美国环保署(EPA)推荐的健康风险评价模型进行重金属呼吸途径的人群健康风险评价。结果 PM_(2.5)中地壳元素和重金属的平均浓度从高到低分别为:Si>K>Na>Ca>Al>Fe>Mg>Ti,Zn>Pb>Cu>Mn>As>Cr>Ni>Cd;As平均浓度(20.17 ng/m3)超过GB 3095—2012《环境空气质量标准》二级标准限值(6 ng/m3)。地壳元素Na、Ca富集因子(EF)分别为247.45、198.79,富集显著;重金属的EF普遍高于100,其中,Cd的EF高达104。主成分分析结果表明广州市PM_(2.5)元素主要来源于机动车、燃煤排放源、工业源和地壳源。重金属通过呼吸暴露的非致癌风险(HQ和HI)均远小于1,致癌风险均低于10-5。结论广州市普通人群吸入PM_(2.5)中重金属的非致癌风险较低,致癌风险处于可接受水平。

Objective To know the temporal distribution characteristic of concentration of elements in PM2.5 in Guangzhou and to assess the health risks of heavy metals. Methods The PM2.5 samples were collected from three different sites in Guangzhou in four seasons. The concentrations of 16 elements were detected by ICP-MS,the temporal distribution characteristics were analyzed. The health risk assessment of heavy metals in PM2.5 was performed by using the US EPA risk assessment model.Results The annual average concentrations of crustal elements and heavy metal ranked as following： SiKNaCaAlFeMgTi and Zn〉Pb〉Cu〉Mn〉As〉Cr〉Ni〉Cd. The annual average concentration of As（20.17 ng/m3） exceeded the limit（6 ng/m3） of Ambient Air Quality Standard（GB 3095-2012）. The enrichment of Na and Ca in crustal elements was significant and the EF（enrichment factors） values were 247.45 and 198.79, respectively, which were mainly related to the building dust. EFs of heavy metals were generally higher than 100, EFs of Cd reached up to 104. The results of principal component analysis indicated that elements in PM2.5 came mainly from vehicle emissions, coal combustion, crust dust and industrial emissions. The non-carcinogenic risk values HQ and HI of heavy metal exposure through respiration were far less than 1, the carcinogenic risk was lower than 10-5. Conclusion The non-carcinogenic risk of inhalation of heavy metals in PM2.5 is low and the carcinogenic risk is under average acceptable level.